From 4c6cd7a047014ed5072c92d5097d426e347bb283 Mon Sep 17 00:00:00 2001
From: Yura Lazarev <unisay@gmail.com>
Date: Mon, 13 Jul 2026 18:04:12 +0200
Subject: [PATCH] fix: restore the missing Data.Array.ST.clone

Upstream purescript-arrays v7.3.0 exports clone, backed by the
cloneImpl :: STFn1 (STArray h a) h (STArray h a) foreign, but the fork
tracked the 7.3.0 sources with neither the export nor the foreign, so
code written against the registry package failed to compile against the
fork ("Unknown value clone"). Restore the declarations as upstream
states them and bind cloneImpl to the same independent copy the FFI
already uses for thawImpl/freezeImpl; the regression guard now covers
it.

Refs purescript-lua/purescript-lua#267.
---
 changelog.d/20260713_180352_st_clone.md |  7 +++++++
 src/Data/Array/ST.lua                   |  1 +
 src/Data/Array/ST.purs                  | 10 ++++++++++
 test/regression/array_st.lua            |  9 +++++++++
 4 files changed, 27 insertions(+)
 create mode 100644 changelog.d/20260713_180352_st_clone.md

diff --git a/changelog.d/20260713_180352_st_clone.md b/changelog.d/20260713_180352_st_clone.md
new file mode 100644
index 0000000..9d5ae27
--- /dev/null
+++ b/changelog.d/20260713_180352_st_clone.md
@@ -0,0 +1,7 @@
+### Fixed
+
+- `Data.Array.ST` exports `clone` again: upstream v7.3.0 declares
+  `clone`/`cloneImpl` (`STFn1`), but the fork carried neither, so code using
+  `Data.Array.ST.clone` failed to compile against the fork. The Lua module
+  now provides `cloneImpl`, the same independent copy the FFI already uses
+  for `thawImpl`/`freezeImpl`.
diff --git a/src/Data/Array/ST.lua b/src/Data/Array/ST.lua
index c92ddf3..011b5c7 100644
--- a/src/Data/Array/ST.lua
+++ b/src/Data/Array/ST.lua
@@ -73,6 +73,7 @@ return {
   unsafeThawImpl = (function(xs) return xs end),
   freezeImpl = (copyImpl),
   thawImpl = (copyImpl),
+  cloneImpl = (copyImpl),
   sortByImpl = ((function()
     local function rshift(x, by) return math.floor(x / 2 ^ by) end
 
diff --git a/src/Data/Array/ST.purs b/src/Data/Array/ST.purs
index 0e9370f..e1395a8 100644
--- a/src/Data/Array/ST.purs
+++ b/src/Data/Array/ST.purs
@@ -24,6 +24,7 @@ module Data.Array.ST
   , sortWith
   , freeze
   , thaw
+  , clone
   , unsafeFreeze
   , unsafeThaw
   , toAssocArray
@@ -95,6 +96,15 @@ thaw = runSTFn1 thawImpl
 -- | Create a mutable copy of an immutable array.
 foreign import thawImpl :: forall h a. STFn1 (Array a) h (STArray h a)
 
+-- | Make a mutable copy of a mutable array.
+clone
+  :: forall h a
+   . STArray h a
+  -> ST h (STArray h a)
+clone = runSTFn1 cloneImpl
+
+foreign import cloneImpl :: forall h a. STFn1 (STArray h a) h (STArray h a)
+
 -- | Sort a mutable array in place. Sorting is stable: the order of equal
 -- | elements is preserved.
 sort :: forall a h. Ord a => STArray h a -> ST h (STArray h a)
diff --git a/test/regression/array_st.lua b/test/regression/array_st.lua
index 0172e65..f370935 100644
--- a/test/regression/array_st.lua
+++ b/test/regression/array_st.lua
@@ -69,6 +69,15 @@ do
   check("thawImpl is independent", copy[1] == 1, "copy mutated to " .. tostring(copy[1]))
 end
 
+-- cloneImpl (the same move-to-fresh-table path) is an independent copy.
+do
+  local xs = {1, 2, 3}
+  local copy = ST.cloneImpl(xs)
+  checkArray("cloneImpl copies", copy, {1, 2, 3})
+  xs[1] = 99
+  check("cloneImpl is independent", copy[1] == 1, "copy mutated to " .. tostring(copy[1]))
+end
+
 -- toAssocArrayImpl builds zero-based {index, value} records.
 do
   local r = ST.toAssocArrayImpl({"a", "b"})